Chiang Mai Journal of Science

     The goal of this study was to develop pregelatinized starch (P-St) and polyvinyl alcohol (PVOH) films as water-soluble laundry plastic bags to avoid having contact with COVID-19 infected clothes by extrusion method. The effects of pregelatinized starch (P-St) content on the properties of polyvinyl alcohol (PVOH) films were examined. PVOH and P-St blend were compounded by twin-screw extruder with various P-St content of 0, 10, 20, 30, and 40% by weight with fixed glycerol content of 20 phr. The blend films were produced by blown film extrusion. The chemical structure, thermal properties, water-solubility, mechanical properties, and the cross-sections morphological properties of PVOH/G/P-St were characterized. As a result, the formation of intermolecular interactions between PVOH, glycerol and P-St was confi rmed by FTIR. Moreover, the addition of P-St on PVOH could reduce the thermal stability due to the content of P-St with amylose, a substance of amorphous structure, affecting the chains flexibility of PVOH/G/P-St. From the differential scanning calorimeter result, the glass transition temperature was increased with the increment of P-St content because the chains entanglement between PVOH and P-St had affected the reduction in crystallinity and led to the decrement of the melting temperature. Furthermore, the water solubility would strongly be dependent on the percentage of the gelatinized starch (%GS). The solubility decreased as the percentage of the GS increased. In addition, PVOH with 20% of P-St film possessed the highest value in tensile strength and modulus, and the particles of P-St have a good distribution in PVOH/G indicating to stronger interaction of P-St and PVOH/G.